1. Field of the Invention
The present invention relates to an image reading apparatus configured to read a document positioned on a document positioning plate, and a cover assembly for use with an image reading apparatus configured to cover a document placed on a document positioning plate.
2. Description of the Related Art
Conventionally, most document covers (original covers or platen covers) attached to conventional image reading apparatuses are configured to be opened at one position. However, if a document having a size larger than that of a document positioning glass plate is placed thereon, the document sometimes cannot be properly positioned on the document positioning plate because of the document cover opening only up to approximately 90 degrees.
U.S. Patent Application Publication No. US 2006/0139703 A1 discusses an image reading apparatus having a configuration in which two positions are provided for a pivot that couples a document cover to the image reading apparatus. In this configuration, the pivot can be moved between the two positions to switch between the state in which the document cover is open at an angle of approximately 90 degrees and the state in which the document cover is open at an angle of 180 degrees or more. Japanese Patent Application Laid-Open No. 2006-184691 discusses a configuration in which the angle of a document cover at the open position can be changed.
In one conventional method for moving the position of the pivot of a document cover to change the open angle of the document cover, operations for moving the pivot are difficult for a user to understand, and it is also difficult to identify where the pivot is positioned. If the document cover is maintained to be open at an angle slightly larger than approximately 90 degrees, a force to further open the document cover due to its own weight acts on an open angle restricting portion of a bearing. Therefore, the strength of the bearing is required to be increased.
Japanese Patent Application Laid-Open No. 2006-184691 suggests that a first component to prevent a document cover from being open at an angle equal to or larger than a specified angle and a second component that acts as a stopper for the first component can be moved to change the opening and closing angle of the document cover. However, it does not discuss any particular configuration.